Contact finger



April 24, 1928. j

' F. E'. CASE CONTACT FINGER Filed April 22. 1925 Inventor. Frank ECcxse, bg MW His Attorneg Patented Apr. 24, 1928.

1 UNITED STATES PATENT OFFICE.

rnaivx ni'ca'sn, or sc'rrn'NEcrADY," NEW YORK, assrenon vTo GENERAL" nnnc'rnic COMPANY, A CORPORATION or NEW YORK.

CONTACT rrivena.

Application filed April 22, 1925. Serial No. 25,151.

This invention relates to electrical contacts, and more particularly to contact fingers for drum controllers and the like wherein the contacts are subjected to severe wear from abrasion and arcing.

The present invention provides an improved form of contact which remains serviceable even after the original contact surface is worn completely through. 1

It has been heretofore proposed to form controller contact fingers of a strip of flexible metal such as steel or the like, with one end bent or crimped to form an intermediate contact surface. However, if such a contact isallowed to operate too long it wears through at the point of contact, and the end I breaks off with possible damage to the segments of the controller.

Controller contact fingers constructed in accordance with the present invention do not permit the ends of the fingers to fall off when the contact wears completely through and consequently the fingers will continue to operate satisfactorily without damage to the controller segments until replaced during the periodic inspection of the controller. Thus my improved form of contact finger effectively prevents accidental interruption of service due to wearing through of the contacts and materially reduces the periodic inspection and replacement ordinarily required for satisfactory service.-

The invention may be carried into effect in a preferred form, as shown in the accompanying drawing, in which the single figure is a perspective view of a drum controller contact finger embodying the invention, together with a cooperating controller segment.

In the drawing contact finger 10 is provided at one end with suitable holes for receiving the screws 11 and 12, which secure the finger, as well as the terminal 13, to the support 14:. In the preferred form illustrated the free end of the contact finger 10 is bent to form an intermediate contact surface 15 having the diverging sides 16 and 17, and the end 18 of the finger 10 is looped back into engagementwith the main body or stem of the finger In order to prevent the side 17 from falling off when the contact surface 15 wears through the looped back end 18 is secured to the body of the finger, preferably by welding or copper brazing.

contact surface.

either direction, one or the other of the diverging sides 16 and 17 is engaged by one end of the segment 19 and the finger 10 yields to permit continued rotation of the segment 19. The contact surface 15 of the finger 10 is pressed into firm contacting'en gagement with the surface of the segment 19 as the latter is rotated in either direction. It will be evident that upon continued sliding of the contact surface 15 upon the segment. 19 the resulting abrasion of the contact surface 15 gradually wears away the original When the contact surface 15- is completely worn through, the side 17 cannot drop ofl. due to the fact that the end 18 is secured to the body of the finger. Thus the sides 16 and 17 are maintained inoperative relation even though the original contact surface 15 is completely worn through, and no damage can result to the controller through stubbing ofthe ends. of the segment 19 against the finger 10 or through dropping of the side 17 into short circuiting relation with other contact segments of the controller.

While I have described the end 18 as welded or copper brazed to the body of the finger 10, it will be understood that the. end 18 may be riveted or otherwise secured to the finger 10 if desired. I

With my improved form of contact finger wearing through of the original contact surface does not. render the finger incapable of further satisfactory service and hence the finger may be continued in service until the periodic inspection discloses the Worn condition of the finger so that'replacement can then be made.

.What I claim as new and desire to secure by Letters Patent of the United States is 1. A contact finger comprising a metal strip having a free end bent to form an intermediate oflset contact portion with diverging sides and provided with means for maintaining the said diverging sides of the offset portion in operative relation when the contact portion wears through.

2. A contact fin ger comprising a metal strip having one end bent to form an interhaving the other end bent to form an offset mediate offset contact surface and looped contact surface with diverging sides and back into engagement with and secured to looped back into contact with an intermedi- 10 the body ofthe strip. ate portion of the strip and secured thereto.

3. A unitary contact finger comprising a In Witness whereof, I have hereunto set flexible metal strip provided at one end my hand this 21st day of April, 1925. with means for supporting the finger and FRANK E. CASE. 

